What a wonderful colorful autumn we’ve had this year, the city a blaze of colored tree and shrub leaves.

Why is this year different from others? Mainly because we’ve had bright, sunny days, cool nights and, according to Tim Wilson of Cloverdale Nursery, no super hard freezes.

As the Earth tilts away from the sun our daylight hours diminish, and we’re now in the truly dormant time of fewer than ten hours of sunlight per day. As we approach this time, the bond between the leaf stalk and its twig grows corky (the abscission layer), cutting off nutrients that would have kept renewing chlorophyll. Chlorophyll is the green that most leaves exhibit during the growing season, but it masks other colors within the leaf.

When chlorophyll green fades away, leaves reveal the carotene (yellow) and xanthophyll (orange) colors that have been there unnoticed all summer. These pigments are also responsible for the colors of daffodils, carrots and pumpkins.

Fall leaves also exhibit vivid reds and purples, thanks to anthocyanins, manufactured by sugars left in the leaves. These are especially noticeable during bright cool autumns. Anthocyanins are also responsible for the red of apples and cranberries, the blue of blueberries, etc. In leaves at least, the more alkaline the sugar-sap in the leaves, the more purple to blue the color. Sugar-sap of reds is an acidic substance.

Expert sources say well-watered trees and shrubs, plus bright sunshine and cool nights create a colorful display, but our “well-watered” status is due to homeowners and park maintenance folks’ supplemental watering since we’ve just come through one of the driest summers on record: .31 inch of precipitation between June 1 and Sept. 30.

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Now, before many seed catalogs have arrived, turn your garden attention to your tools. Clean mud and dirt off your shovels, spades, spading forks and hoes, and remove any rust that’s formed. Rust creates friction with soil making you work harder as you use that tool.

To remove rust, use wire brushes and/or emery paper. Once that metal has been cleaned, sharpen the tool following the beveled edge with a flat mill file with a bastard cut (upper right to lower left as you face the file). If your regular hoe doesn’t have a beveled edge, it was really intended for cement mixing, not weeding. I used to use this kind of tool to manipulate flats of plants in the bed of my pickup, but never liked it for weeding. I prefer the oscillating stirrup hoe, also known as a Hula hoe.

Once these metal surfaces have been cleaned and sharpened, spray them with WD-40 to preserve their finish, then turn your attention to the long handles of your tools.

Wooden handles should be oiled for preservation. Some use boiled linseed oil, but beware of this because rags and papers used to apply linseed oil may spontaneously burst into flame. Some folks use safer motor oil, cheap vegetable oil or mineral oil for the handles.

Clean hand tools, too. Clean sap gunk from your bypass pruners and loppers with emery paper or SOS pads, wash soap from the blades if you used the latter, rinse and dry.

Then use a stone to sharpen blades, again following the original bevel. There are tools available to guide round sharpeners to the right angle for pruners and loppers.

Margaret Lauterbach: melauter@earthlink.net or write to Gardening, The Idaho Statesman, P.O. Box 40, Boise, ID 83707